Earnings per Share - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Net income	$ 33,717	$ 32,066	$ 99,267	$ 59,011
Preferred stock dividends	10	10	30	30
Net income available to common equity	33,707	32,056	99,237	58,981
Dividends and undistributed earnings allocated to participating securities	32	36	94	62
Net income available to common shareholders	$ 33,675	$ 32,020	$ 99,143	$ 58,919
Basic weighted-average shares outstanding	38,417	38,074	38,328	37,970
Stock options and other stock compensation	619	628	586	722
Diluted weighted-average shares outstanding	39,036	38,702	38,914	38,692
Antidilutive stock options	0	0	0	0
Earnings per share:
Basic	$ 0.88	$ 0.84	$ 2.59	$ 1.55
Diluted	$ 0.86	$ 0.83	$ 2.55	$ 1.52